Critical Crossover Behavior of Itinerant Weak Antiferromagnets around Quantum Critical Point

Abstract

Magnetic and thermal critical behaviors
of itinerant electron magnets around the quantum
critical point (QCP) have recently attracted much
interest. On the other hand, crossover phenomena
between classical and quantum critical behaviors have
not drawn much attention. The purpose of this study
is, therefore, clarifies how the predominance of
thermal and quantum critical behaviors will change
around the QCP based on the spin fluctuation theory.
We show that in the region very close to the Neel
temperature TN in the paramagnetic phase, the
temperature dependence of the inverse of staggered
susceptibility obeys the classical (T-TN)2-linear
behavior. With increasing temperature T, it changes
into the quantum critical (T3/2-TN
3/2)-linear
dependence above the crossover temperature T*.
Since T* tends to vanish in the quantum critical limit
TN  0, the classical critical region disappears and
predominant T3/2-linear behavior prevails.